BN-G-Y017 Welding Inspection

Table of Contents

1. Scope
2. Applicable Codes
3. Welding Procedures and Welders Qualifications
4. Inspection Requirements
5. Weld Joint Preparation
6. Heat Treatment
7. Radiographic Requirements
8. References

FORMS (Typical Example Attached)

26C30 Inspection Record for Site Welding

26C31 Weld Repair Report

26C32 Inspection Record for Field Welds

26C33 Radiograph Inspection Report

26C34 Radiography Record Sheet

26C35 Record of Welder Performance Qualification Test on Groove Welds

1. Scope

The purpose of this section is to provide guidelines to Company personnel, in particular to the Welding Engineer, concerning the welding, heat treatment and weld inspection of:

• Prefabricated piping.

• Field welding of prefabricated piping.

• Field welding of random length piping.

• Field welding of pipe to vessel stub-ends (e.g. furnaces or in some cases vessel to vessel stub-ends due to transport limitations).

(Whilst this section is written in terms of welding associated with piping, the same general principles apply to welding of structural steelwork and of storage tanks).

Primary responsibility for quality is that of the subcontractor who shall satisfy himself through his own quality system that specified requirements are met.

It is the responsibility of the Welding Engineer to ensure that the subcontractor is in fact effectively applying his quality system and obtaining acceptable results.

The following specialist organizations are also implicated:

• Non destructive and destructive testing firms.

• Possibly third party inspector to meet Authorities requirements.

Depending on the particular project, their services may be included in the piping subcontractor's scope or alternatively they may be directly controlled by Company.

Piping generally involves onsite or offsite prefabrication of spools. This activity may in some circumstances be part of a construction subcontract and controlled from site.

It is important that the quality systems put into place for welding and heat treatment of piping adequately cover the activities of these specialist organizations and of the prefabrication shops. Responsibility for their day-to-day supervision is that of the Welding Engineer.

Subsequent sections 17.3 to 17.7 are in effect checklists of points requiring surveillance, inspection or testing. They are intended as a reminder and a help to the Welding Engineer. However, they are no substitute for reading and familiarizing oneself with the subcontract, requisitions, specifications, standards and drawings. In case of conflict it is these project specific documents which prevail.

The subcontractor creates his own quality system, which includes proposing the inspection and testing record forms to be used. Their suitability shall be judged by the Quality Assurance Manager in consultation with the Welding Engineer (see Reference 17.8.1).

The set of inspection and test record forms attached to this section:

• May be used as a basis to review the subcontractor's forms.

• May be imposed on the subcontractor should the latter's forms be considered to be unsuitable.

2. Applicable Codes

• ASME Boiler and Pressure Vessel Code, Section VIII, latest issue, or specified equivalent.

• American National Standard Code for Pressure Piping ANSI B 31.3, or specified equivalent.

• ASME Boiler and Pressure Vessel Code, Section IX, latest issue, or specified equivalent.

• Specifications applicable to the job in question.

• Clients specifications and additional requirements.

• Authority requirements (e.g. T.U.V., Stoomwezen, etc.)

3. Welding Procedures and Welders Qualifications

All welding procedure specifications and procedure qualification records shall be submitted by the subcontractor(s) to Company for review and approval.

Welders performance qualifications shall be in accordance with applicable procedures, codes, etc. as laid down in 17.2 of this procedure. A copy of the performance qualification test record showing the name of the employer by whom the welder or welding operator was qualified, the date(s) of such qualification and the date the welder last welded pressure piping components under such qualification must be obtained from the previous employer.

Renewal of qualification of a performance specification is required:

1. When a welder or welding operator has not used the specific process, i.e., metal-arc, gas submerged arc, etc. for a period of three (3) months or more.

2. When there is specific reason to question his ability to produce welds that meet the specification.

When welder qualifications are not available or on request of client, it is allowable to have the welder perform a testweld. It is necessary in this case to perform a guided bend test as described in ASTM E 190-64. The performance of every welder who is newly qualified shall be checked initially more than other welders by means of NDE (see Reference 17.8.2).

The Company Welding Engineer can authorize changes in non-essential variables in accordance with section IX of the ASME code and/or other governing codes after approval by client's inspection representative. Such changes do not require the qualification of the procedure in question. However, changes in essential variables not only require requalification but also prior approval by home office Engineering Department and client.

4. Inspection Requirements

Definition of welding inspection: A phase of quality control which by means of examination, observation, or measurement determines the conformance of materials, supplies (gases, electrodes and/or other consumables) parts, components, systems, processes to predetermined quality requirements.

The Welding Engineer shall ensure that welding inspection personnel, whether of the piping subcontractor, of the latter‘s own subcontractor or of a third party shall be adequately qualified and experienced to a recognized standard.

The following is a list of items to be checked or verified to assure correct field welding. The Welding Engineer shall check the following:

a. Qualification of welders

• Validity of welders' certificates.

• Names of welders whilst at work and if identification marks along completed welds check with qualification.

b. Weld numbering

• Welds are numbered according to approved numbering system and that ISO's and drawings are marked-up with this number.

c. Requirements to be met before welding starts

• Proper storage and handling of welding materials.

• Use of correct welding rods or wires.

• Use of hot-boxes for low-hydrogen welding rods.

• Assignment of qualified welders as per above.

• Application of adequate WPS (welding procedure specification).

• Protection against weather conditions.

• Back purging for alloy steel.

• Pre-heating.

• Check that proper equipment will be used. (e.g. welding machines, purge gases and their associated equipment, heat pre- and after treatment including temperature recording apparatus).

• Material check i.e. materials on both sides of weld comply with that in WPS (for further details see Reference 17.8.2).

• Proper transfer of heat numbers (if required by specification and/or authorities).

d. Examination of welding work and weld preparations

1. Root opening

- rootface and shape of groove

- cleanliness

- misalignment

- removal of tack weld

2. Rootpass

- check for cracks, porosity

- remove slag

- remove sharp ridges (grinding to avoid lack of fusion

- repairs if necessary

- dye penetrant test and/or other NDE if required by WPS (e.g. for heavy wall pipe)

3. Subsequent weld layers

4. Visual final checks

- undercut

- configuration of cover passes

- crater defects

- surface porosity

- slag removal

- stamp of welder and field weld no. is in place near weld

- repairs if required

5. NDE as prescribed in specification

6. Post weld heat treatment (alloy and heavy wall piping)

7. NDE as prescribed in specification (alloy and heavy wall piping)

- hardness tests

The work as described under d.1 through d.7 above will be done in the sequence given and between the points d.1 through d.5 there will normally be a holdpoint of the subcontractor between each point till inspection has taken place before proceeding with the next item. The Welding Engineer will determine which items constitute Company holdpoints.

Butt-welds shall, when feasible, also be visually inspected inside, paying particular attention to:

• cracks

• undercutting

• overcrown and

• lack of penetration

Branch-welds shall be visually inspected as specified for butt-welds.

All welds of dummy pipe supports shall be inspected for proper beveling and fit-up after full penetration tack welding, prior to start of root and filler passes.

5. Weld Joint Preparation

Weld bevels shall be made by machining, grinding or thermal cutting and grinding.

The surfaces shall be reasonably smooth and true for good fit-up.

Spacers shall be used while tackwelding pipe and fittings in position to ensure proper gap and full penetration in welding.

Small tack welds shall be used with full root penetration. Make sure that if pre-heating is required that its requirements are met during tackwelding.

6. Heat Treatment

The Welding Engineer shall ensure with the subcontractor that all necessary precautions are taken to prevent distortion during heat treatment.

Heat treatment operations shall be checked for compliance with approved procedures.

The proposed stress relieving method and location of thermocouples shall be defined in a written procedure submitted by the subcontractor to the Welding Engineer for approval.

Thermocouples and a temperature chart recorder shall be used to provide a permanent record of all post weld heat treatments. Observe the gradient of temperature increase as laid down in the specifications.

Thermocouples shall not be in direct contact with electrical heating elements or subjected to flame impingement by gas burners.

Thermocouples shall, if applicable, be placed on the inside of objects being heated from the outside and vice versa, if internally heated.

At least two thermocouples shall be used for circumferential welds on pipe diameters of 24 in. and smaller. These should be placed at the top and bottom of the pipe. Pipes of diameter larger than 24 in. shall have at least four thermocouples.

Threads and gasket surfaces shall be protected from oxidation during heat treatment.

After heat treatment, welding or heating is not permitted, if no re-heat treatment is performed. (Re-heat treatments shall be limited to two times).

Hardness testing, shall not be done until the pipe has reached ambient temperature.

Hardness tests shall be carried out as near to the weld heat affected zone as possible.

7. Radiographic Requirements

Radiographic requirements shall be in accordance with the relevant pipe classes and specifications.

The first weld of each welder shall have 100% radiography regardless of pipe diameter and thickness.

Where random X-ray is required, the Welding Engineer shall select locations.

The Welding Engineer shall ensure that the extent of radiography on weld and per welder meets the requirements of the applicable specifications, ANSI B 31.3 or equivalent specified code.

NDE examination will be executed after stress relieving.

For further details on X-raying see Non Destructive Examination (see Reference 17.8.2).

8. References